The present invention relates to a solar cell module to be connected to a cable for connecting the solar cell modules to each other, a method of connecting the solar cell module, a method of installing a plurality of solar cell modules on an installing body such as the roof of a house without using a rack, a solar cell module to be connected to a ground wire for making a ground connection, and a method of grounding the solar cell module.
Photovoltaic power generation for converting light energy into electrical energy by using a photoelectric conversion effect has been widely used as means for obtaining clean energy. Besides, with an improvement of the photoelectric conversion efficiency of solar cells, the number of private houses using a photovoltaic power generation system has been increasing.
In such a photovoltaic power generation system, a plurality of solar cell modules, each comprising a solar cell portion where a plurality of stages of solar cells are connected in series, are connected to a trunk cable, and a DC output of the solar cell modules collected through the trunk cable is converted into an AC output by an inverter and the AC output is outputted.
There is a known method of connecting solar cell modules, which facilitates wiring in connecting a plurality of solar cell modules to a trunk cable (for example, Japanese Patent Application Laid-Open No. 11-299126/1999). According to this conventional connecting method, the solar cell module can be easily connected to the trunk cable by connecting a male connector or a female connector provided on the trunk cable to a female or male connector provided on the solar cell module.
In the above-mentioned conventional method of connecting solar cell modules, there is a problem that the male and female connectors become expensive in order to improve their waterproof performance, and there is also a room for improvement of the waterproof performance at the connected section.
Moreover, in a photovoltaic power generation system for private houses, a technique of installing a plurality of solar cell modules directly on a building material of a roof (sheathing roof board) without using a rack has been employed in addition to a technique of installing a plurality of solar cell modules on a metal rack.
In order to make the appearance of the solar cell modules similar to the roof, the method of installing a plurality of solar cell modules on the sheathing roof board often employs a so-called stepped-roofing structure in which a plurality of solar cell modules are installed stepwise from the ridge side toward the eave side in such a manner that the ends of adjacent solar cell modules overlap each other. In this case, since the waterproof property is obtained by engagement of adjacent solar cell modules, it is difficult to replace the solar cell modules on a piece by piece basis, and thus there is a problem that this method can not respond efficiently to a breakdown or installation defect of the solar cell modules. Furthermore, there are problems that the installation involves complicated work processes and it takes a long time to perform the processes.
In the case where a plurality of solar cell modules are installed on a metal rack, since a metal frame portion on the periphery of the solar cell module is fixed to the rack, the periphery of each solar cell module and the rack have an equal electric potential, and therefore each solar cell module can be grounded if the rack itself is connected to a ground wire. On the other hand, when a plurality of solar cell modules are installed directly on the building material of the roof (sheathing room board), since the rack is not provided, it is necessary to additionally provide a wire for connecting each solar cell module to the ground wire on the periphery of each solar cell module so as to ground the solar cell modules, and there is a demand for simplicity of connection with the ground wire.